This patent application claims the benefit of Finnish Patent Application No. 20021060, filed Jun. 3, 2002, which is incorporated in its entirety herein by this reference.
1. Field of the Invention
The invention relates in general to piercing mechanisms and methods for using the same and in particular to piercing mechanisms usable in rescue booms and methods for feeding fire-retardant medium.
2. Background of the Invention
In fire fighting, it is very important to start fire-fighting measures promptly before the fire expands so that it cannot be controlled. In the case of an air crash, for example, the fire should be brought under control within the first few minutes from the onset of fire. In that case, ideally, the fire-fighting equipment is brought to the scene as fast as possible and the fire-retardant medium is quickly fed inside the object on fire without having to break down the structures. Thus, rescue booms have been devised that are placed on a movable carrier and provided with a piercing tool which can be pushed through the wall structure of the object on fire. Examples of prior piercing tools are disclosed in U.S. Patent Nos. 5,211,245; 5,301,756; 5,788,158; and 5,839,664.
The piercing tool can include a sharp point which pierces the body structures of vehicles and the like relatively easily. After piercing, fire-retardant medium can be fed directly into the object on fire. In existing devices, piercing is carried out by moving the boom parts with respect to their joints or by extending telescopic boom parts. A problem associated with operating conventional piercing tools via boom movements is that it is difficult for the user to control the boom to achieve the necessary piercing movement. Furthermore, the user does not sense the movements of the boom, which in turn can prevent his noticing whether forces are directed to the piercing tool that could damage it.
The present invention provides a new and improved arrangement for piercing a wall shell structure with a piercing tool. The present invention is particularly useful in fire fighting. The method of the invention maintains a rescue boom in a substantially stationary position during a piercing operation carried out by driving a piercing tool through a wall shell structure by means of an actuator provided at the end of the rescue boom.
The boom can be provided with at least one piercing device, which comprises at least one elongated piercing tool. The piercing device can be mounted to the rescue boom. The piercing device can include at least one actuator for moving the piercing tool in its longitudinal direction. The piercing tool can move along its longitudinal direction with respect to the outermost end of the boom. The actuator can generate a longitudinal movement in the piercing tool, without moving the boom, for advancing the tool through a wall shell structure confining a fire. With the piercing tool being punched through the wall shell structure by a quick longitudinal movement, the forces needed for piercing can be relatively small.
An advantage of the invention is that the actual piercing is carried out by a separate actuator and, unlike in prior art solutions, without moving the boom. It is considerably easier and faster to carry out piercing by the piercing tool of the present invention than by moving a long boom. Furthermore, damage to the piercing tool can be avoided.
The actuator can include at least one spring member for punching the piercing tool through the wall shell structure. In another aspect of the invention, the actuator can include at least one pressure medium cylinder for pushing the piercing tool with respect to the boom end.
A front end of the piercing device can be provided with a plunger, which can be pressed by a pre-determined force against the wall structure for the piercing thereof such that the yielding of the wall structure from the piercing forces can be avoided. Furthermore, the plunger may locally deform the place to be pierced, which also facilitates the piercing.
In one aspect of the invention, a method for feeding fire-retardant medium from a first side wall of a shell structure to its second side is provided. The outermost end of a rescue boom can be positioned in the immediate vicinity of the first side of the shell structure. The shell structure can be pierced by pushing at least one elongated piercing tool provided at the outermost end of the rescue boom. At least a portion of the piercing tool can be pushed from the first side of the wall structure to the second side thereof. Fire-retardant medium can be fed through at least one longitudinal channel provided in the piercing tool and through at least one nozzle connected to the channel out of the piercing tool within the space bound by the second side of the shell structure.
In another aspect of the invention, a rescue boom can include one or more moveable boom parts. The rescue boom can include a first end connected to a carrier and a second end, which is furthest away from the carrier. A piercing tool can be provided adjacent the second end of the boom. The piercing tool can be an elongated member having at least one longitudinal channel. A feed channel can be provided for feeding fire-retardant medium into the channel of the piercing tool. A nozzle can be provided which is connected to the channel of the piercing tool for feeding the fire-retardant medium therethrough. Means for adjusting the angular position of the piercing tool with respect to the outermost end of the boom can also be provided.
In yet another aspect of the invention, a piercing device can be provided which includes a piercing tool in the form of an elongated member having a longitudinal channel, a feed channel for feeding fire-retardant medium into the channel, and a nozzle which can be connected to the channel and through which the fire-retardant medium is arranged to be fed.